Field of the Invention
The present invention relates to surgically implanted devices for fixation of human bones and associated tissue, and particularly to surgically implanted devices for fixation of metatarsal bones and associated tissue. More particularly, the present invention relates to surgically implanted devices for internal fixation of a distal portion of a metatarsal bone with a metatarsal diaphysis along with any capsular corrections.
Background
The distal metatarsal metaphysis of the human foot is a very common site of fracture as well as repositional osteotomy for correction of deformities as well as other reasons. Osteotomy to provide shortening of a metatarsal is commonly performed to decrease plantar forefoot pressure at the site of a metatarsal head. Shortening osteotomy is most commonly performed on central metatarsals. Shortening the metatarsal shortens the lever and decreases the pressure at the plantar forefoot generated during the propulsive phase of gait. Shortening osteotomy can alleviate pain caused by excessive pressure due to a relatively long metatarsal. Shortening osteotomy can also help heal plantar skin keratosis or ulceration due to excessive pressure. Shortening osteotomy is often performed in combination with hammertoe corrective procedures.
Stable fixation of the metatarsal head fragment to the diaphysis (shaft) of the metatarsal in order to provide appropriate correction and ideal anatomic osteotomy location can be challenging and inadequate with current devices available. Osteotomy orientation has currently evolved to facilitate fixation while sacrificing ideal correction and ideal osteotomy anatomic location. A pure segmental shortening osteotomy performed at the distal metaphysis is ideal but very difficult to fixate. The distal fragment is small and current fixation devices do not adequately fixate this fragment in order to stabilize the metaphyseal osteotomy.
To address this problem, currently a more proximal segmental shortening osteotomy is performed so a dorsal plate can be used with at least two screws to engage the distal fragment. Plates are available with both non-locking and locking screws to engage the bone. This more proximal osteotomy results in diaphyseal bone shortening. Metaphyseal bone has a greater healing potential than diaphyseal bone and is therefore the preferable location for osteotomy. Furthermore, the more proximal osteotomy is potentially stressed by a longer lever distal to the osteotomy.
The most common osteotomy for shortening of the central metatarsals is a long oblique osteotomy from distal dorsal to proximal plantar. This is partially a metaphyseal osteotomy and facilitates fixation from dorsal to plantar with isolated screws or pins. The osteotomy orientation unfortunately often results in plantar displacement of the distal fragment with the shortening. The distal dorsal cortical spike is also subject to fracture at the fixation site which can result in displacement of the osteotomy.
Osteotomies to displace a metatarsal head laterally or medially are often performed to correct bone prominence of the first (hallux abducto valgus/bunion deformity) or fifth metatarsal (tailor's bunion/bunionette deformity) in the transverse plane of the foot. Fixation of the metatarsal head fragment to the shaft fragment is again facilitated by osteotomy orientation. Osteotomy configurations include: oblique, chevron, chevron with longer arm dorsal or plantar, “Z”/scarf and others. Current internal fixation options include: k-wires, screws, plates, wire, staples. These osteotomies are all subject to displacement with current fixation options as the distal fragment is difficult to secure with current devices. The aging population and associated decrease in bone density further increases the potential loss of fixation with current techniques and devices. The problem continues to be inadequate stabilization of an osteotomy due to suboptimal fixation of the metatarsal head fragment.
Moreover, often associated with metatarsal deformities are respective digital deformities. Mal-alignment in the transverse plane includes digits deviated medially or laterally from their proper position. When metatarsal realignment osteotomies are performed, capsular corrections must also be included for realignment of the respective digit. The capsular corrections include releasing or lengthening the tight soft tissue preventing realignment and tightening the capsule/ligament on the side where it is lax. Tightening of the capsule is performed by removing a section or advancing the lax capsule from its original attachment and reattaching. The standard means of securing is sutures. Capsule tightening is difficult when adjacent structures prevent access to the site of repair. Also, suture repair requires exposure. The central metatarsophalangeal joints are particularly difficult to perform capsular balancing due to the adjacent joints medial and lateral restricting exposure.
It is therefore evident from the above that there is a need for a system, device and method for better fixation of a metatarsal osteotomy or fracture.
It is further evident from the above that there is a need for better internal fixation of a distal portion of a metatarsal bone and a diaphysis of the metatarsal bone so as to stabilize an osteotomy or fracture of the metatarsal distal metaphysis.
It is moreover evident from the above that there is a need for a system, device and method for fixation of ligamentous and joint capsular tissue to a metatarsal head particularly in connection with fixation of a metatarsal metaphyseal osteotomy or fracture.